Picosecond time-resolved light scattering from coherent exciton states

J. M. Hvam, I. Balslev, Claus Dörnfeld

H. Stolz, Detlef Schwarze, Wolf von der Osten +1 more

В. С. Днепровский, Valentin N. Chumash, E. V. Zimenko

H. Stolz

H. Stolz

Utilizing transform-limited time-resolved light scattering with simultaneously optimum temporal and spectral resolution, it is possible to investigate on a picosecond time scale energy and phase relaxation processes of excitons in semiconductors. Thereby quantum-beating as a measure of exciton coherence allows us to discriminate Raman scattering from hot luminescence as exemplified for indirect free excitons in AgBr. In order to distinguish resonant Rayleigh scattering occurring in disordered systems from ordinary fluorescence, the experimental setup has to be fully included in the theoretical description of the light scattering process. Experiments at the (n equals 1, e-hh) exciton in GaAs/AlGaAs quantum well structures confirm the predicted finite decay of this process and allow us to measure the exciton relaxation dynamics.

Gaël Nardin, Konstantinos G. Lagoudakis, Michiel Wouters +6 more

We report on time-resolved measurements of the first order spatial coherence in an exciton-polariton Bose-Einstein condensate. Long-range spatial coherence is found to set in right at the onset of stimulated scattering, on a picosecond time scale. The coherence reaches its maximum value after the population and decays slowly, staying up to a few hundred picoseconds. This behavior can be qualitatively reproduced, using a stochastic classical field model describing interaction between the polariton condensate and the exciton reservoir within a disordered potential.